In such printing machines it is known (see, for example, my copending application Ser. No. 538,560 filed 6 Jan. 1975 as a continuation of abandoned application Ser. No. 348,703 filed 6 Apr. 1973) to provide a horizontal supply tube for dyestuff to be fed to an applicator mounted on that tube within the cylindrical printing screen. Since the tube is unsupported within the screen, it may experience flexural deformation under its own weight and that of the liquid dyestuff, thereby exerting stresses upon the applicator which result in an uneven contact pressure on the inner screen surface.